1. Field of the Invention
The present invention relates to an incident-light controlling apparatus.
2. Description of the Related Art
In recent years, with an achievement of high image quality of a portable equipment having an image pickup function and a small size image pickup equipment such as a micro videoscope, with regard to optical elements such as a lens, an aperture, and an optical filter, there has been increasing demand for an application of a focusing lens, a variable aperture, and a variable characteristic filter instead of a conventional fixed focusing lens, a fixed aperture stop, and a fixed characteristic filter, and many proposals have been made as a method for making small optical elements to be used in a small size image pickup equipment.
As an example of such variable aperture, in Japanese Patent Application Laid-open Publication No. Hei 10-20360, a coil in which, a film of a substance having a substantial magnetic permeability is let to be a core, is formed on a printed board, with the substrate as a multi-layered substrate structure. A rotor having a hollow circular cylindrical shape which is magnetized at least to bipolarity is fitted in a coil body formed in such manner, and a blade member which adjusts an amount of light passing through is fixed to this rotor via shaft.
Moreover, without restricting to Japanese Patent Application Laid-open Publication No. Hei 10-20360, in a conventional technology, by a coil in which, core made of a magnetic body and a circular cylindrical shaped permanent magnet which is magnetized at least to bipolarity is subjected to winding, a rotational force is imparted to the permanent magnet.
However, in the invention disclosed in Japanese Patent Application Laid-open Publication No. Hei 10-20360, since a film of a substance having a substantial magnetic permeability is let to be the corer there is a magnetic attraction generated all the time between the permanent magnet and the core. For imparting a rotating force to the permanent magnet by passing an electric power to the coil in this state, it is necessary to reverse the magnetic force inside the core which is generated by the permanent magnet, and to create a magnetic pole of a opposite polarity at a coil end portion.
Normally, when a length of the core is sufficiently long, and when it is possible to secure a sufficient number of turns of the coil, by letting the structure to be such a structure, it is possible to use effectively the magnetic power which is generated by supplying the electric power to the coil. However, when it is necessary to make extremely small the incident-light controlling apparatus including the coil, it is difficult to achieve sufficient magnetic power by the core length and by passing the electric power to the coil.